Bags



R. E. HRTIG Aug. 31, 1965 BAGS 3 Sheets-Sheet 1 Filed Feb. 6, 1963 FIGA.2?

Wm www/f ,Jfm- FIGS. MW. Y

Allg- 31, 1965 R. E. HARTIG 3,203,623

BAGS

Filed Feb. e, 195s s sheets-shea 2 l lI R. E. HARTIG BAGS Aug. 31, 19653 Sheets-Sheet 3 Filed Feb. 6, 1963lbbooouannoncenoooooooaeeuanoveanaoauuc u e SSQQGSOSOSOGGQSS@ UnitedStates Patent O 3,203,623 BAGS Richard E. Hartig, Edina, lvinn.,assigner to Bemis Bro. Bag Company, Minneapolis, Minn., a corporation ofMissouri Filed Feb. 6, 1963, Seix No. 259,770 l Claim. (Qi. 229-625)rThis invention relates to bags, and more particularly to multiwallvalve bags.

The invention is particularly concerned with multiwall valve bags forpackaging materials such as, for example, pelletized polycarbonateresin, which must be kept in a very dry state until such time as theyare needed. For example, it is important that polycarbonate resin bedelivered to customers with a moisture content no highe than 0.025%.Heretofore, such material has been packed in cans to prevent the ingressof moisture. Among the several objects of this invention may be notedthe provision of a multiwall valve bag adapted eifectively to seal outmoisture so as to keep the bag contents dry; the provision of a bag ofthis class which inhibits migration of moisture from the bag materialitself into the contents; and the provision of an improved valveconstruction which prevents the ingress of moisture therethrough afterthe valve has been closed. Other objects and features will be in partapparent and in part pointed out hereinafter.

The invention accordingly comprises the constructions hereinafterdescribed, the scope of the invention being indicated in the followingclaims.

in the accompanying drawings, in which several of various possibleembodiments of the invention are illustrated,

FIG. l is a perspective View or" a composite multiwall tube from which abag of this invention is made, parts being broken away;

FlG. 2 is a section taken on line 2 2 of FIG. 1, ply thicknesses beingexaggerated;

FlG. 3 is an enlarged section showing the construction of each of theinnermost and outermost plies;

FIG. 4 is a plan View of the valve sleeve of a bag of this inventionprior to its application to the bag;

FIG. 5 is a perspective view of the FIG. l tube showing the valve sleeveapplied at the valve corner of the bag;

FG. 6 is a view in elevation of a finished bag, with parts removed toreduce the height of the view;

FlG. 7 is an enlarged longitudinal vertical section through the valve;

FIG. 8 is a view similar to FIG. 6 showing a modification of the bag;and

FiG. 9 is a view similar to FIG. 7 showing the bag illustrated in FlG.8.

Corresponding reference characters indicate corresponding partsthroughout the several views of the drawings.

Referring to the drawings, there is shown at l in FIG. l a multiwalltube having a length corresponding to the esired bag length. lt will beunderstood that the tube is formed by continuously feeding a multi-plyweb liroug'n a tuber in which the web is formed into a continuous tube.The continuous tube is then transversely cut at bag length intervals toform tubes l. This follows conventional practice in the art of bagmanufacture, utilizing well-known standard esuipment for forming baglength tubing.

Tube 1 is shown in FG. 2 to comprise an outermost ply 3, an innermostply 5 and intermediate plies each designated 7. it will be understoodthat more or less intermediate plies may be provided, the three pliesshown merely being exemplary. The outer ply 3 and the inner ply 5 areeach of multi-ply water-resistant construction, each comprising a layerof paper 9, such as, for example, kraft paper, a layer of thin metalfoil lll, such as, for example, aluminum foil having a thickness ofapproximately 0.0005 inch, laminated to the paper layer by a film i3 yofheat-sealable material, such as polyethylene, with a coating l5' ofheat-scalable material, such as polyethylene, on the foil. The plasticcoating l5 is on the outside face of the outer ply 3 and on the insideface of the inner ply 5. Thus, the inner and outer plies constitulebarriers to transmission of moisture through the tube walls. rEheintermediate plies 7 may consist of the usual kraft paper.

The longitudinal edge portions of the outer ply are overlapped andsealed together as indicated at 17 as by means of a suitable waterproofadhesive. Each of the intermediate kraft paper plies 7 is overlapped andthe longitudinal edge portions thereof pasted together to provide seams19. Kraft paper itself normally has about 6% moisture content, and mayhave even more if the bag is manufactured on high humidity days.Accordingly, provision must be made for preventing such moisture frompassing through the seam of the inner ply to the contents. For thispurpose, the longitudinal edge portions 2l and 23 of the inner ply 5 arepositioned in inside face to inside face relation with the heat-scalableplastic coating l5 on one portion in direct contact with the plasticcoating l5 on the other portion, and the edge portions are hermeticallysealed together as indicated at 24 as by means of a suitable waterproofadhesive or heatsealing the plastic surface together. Thus, moisture isprevented from passing through the seam of the inner plv.

FIG. 4 illustrates a valve sleeve 2'5 per se, in its initial state,prior to application to the bag tube 1. As shown, this sleeve isgenerally rectangular in shape and cornprises, like the plies 3 and 5, alayer of paper 9, a layer of thin metal foil 1l laminated to the paperlayer by a film of heat-scalable material 13, and a plastic coating 15of heat-sealable material covering the thin metal foil 1l. Thus, thesleeve is moisture resistant. The sleeve is provided with two stripes 27and 29 of heat-resistant pressure-sensitive adhesive extending acrossthe sleeve on the paper layer thereof. The adhesive may be aheat-resistant adhesive particularly in the case where material such aspolycarbonate resin mentioned above is to be bagged, since such materialmay be heated to a temperature of 240 F., for example, during theiilling operation, to keep it dry. lf desired the adhesive may be of atype that cures at high temperature. Stripe 27 is located at one end ofthe sleeve and stripe 29 is spaced inward from the stripe 27, located onan intermediate portion of the sleeve. Each stripe of adhesive mayconsist of, for example, a 0.0005 inch thick Mylar carrier strip havingpressure-sensitive adhesive on each side thereof. The stripes areinitially covered by tapes 3i which are peeled od prior to inserting thesleeve inthe tube 1.

The sleeve is folded in half on a longitudinal center line 33, with itsplastic-coated face on the inside, and inserted with itsadhesive-carrying end rst in the valve corner of the bag tube l todispose the stripe of adhesive 27 against the plastic-coated face of theinnermost ply 5 and to cause the sleeve to become adhered thereto (seeFG. 5). Stripe 29 is spaced outward from the end edge of tube l. Thevalve corner of the bag is tucked in to form a valve ap 35, and aportion 25u of the sleeve is folded back on a transverse line 37 lyingsomewhat inward from the inward edge 39 of the valve Hap 35 to extendback outward over the valve flap. This leaves a relative short portion25h of the sleeve extending inward from the inner edge 39 of the valveflap, this portion 251) being secured to the inside of the inner marginof the valve ap by reason of adhesive Z7 securing it thereto. Stripe 29of adhesive overlies the valve ap 35, i.e., the plastic-coated face ofthe outer ply 3, and seals the sleeve to the valve hap. The sealingfunction of stripe 29 pre vents atmospheric moisture which may enterbetween the sleeve and the outer ply 3 from reaching the upper end edgesof the several plies at 39 (see FIG. 7). If this were to happen, themoisture would be conveyed by capillary action down through the plies tothe bottom thereof, where it would either pass through the ends of theplies or needle holes hereinafter described and inoisturize thecontents. As the valve formation is completed, the portion 25b of thesleeve becomes reversely folded on center line 33 as regards the initialfolded condition so that the plastic-coated face 15 of portion 25h is onthe outside of the reversely folded portion 2517. Portion 25a becomesfolded on center line 33 in such manner that the plastic-coated face 15is on the inside. Corners 41 of the sleeve fold over between the sidesof the valve iiap 3S and the bag walls. These are of no consequence, andcould be eliminated, if desired, by trimming off the corners of thesleeve when it is originally made.

The upper end of the tube 1 is closed by a line of stitching 43extending across the top of the bag through the upper margins of theseveral plies of the bag. This line of stitching constitutes the topseam of the bag. It extends through and secures together the uppermargins of the folded sides of the sleeve so that the sleeve is formedinto a tube adapted to receive a filling spout. The stitching is run offthe side of the bag and throughout the length of the outwardly extendingtuck-in portion 23a of the sleeve. A moisture-resistant tape 45constructed like the innermost and outermost plies 3 and 5 and thesleeve 25, i.e., having a paper layer 9, a layer of metal foil 11laminated to the paper layer by a lm of polyethylene 13, and a plasticcoating 15 on the layer of metal foil is folded over the stitching i3with the plastic coating 15 on the inside and heat-sealed to theoutermost ply 3 and sleeve 25 to prevent the ingress of moisture throughthe top of the bag and the needle holes` The lower end of the bag lengthis similarly closed by a line of stitching 47 and a tape 45 to preventthe ingress of moisture at the bottom of the bag. After the bag has beenlled by means of a filling spout extending through the sleeve and intothe bag, the outer end of the sleeve may be heat-sealed closed byheat-sealing the plastic coating 15 of the sleeve together. The sleevemay then be tucked into the bag.

A modified embodiment of the bag is indicated at 51 in FIGS. 8 and 9.This bag is generally the same as the i bag shown in FIGS. 6 and 7, buthas a different valve sleeve construction and a different type of endclosure. The valve sleeve in FIGS. 8 and 9 is designated 53. Like sleeve25, it comprises a layer of paper 9, a layer of thin metal foil 11laminated to the paper layer by a film "i3 of heat-scalable material,such as polyethylene, and a coating 15 of heat-scalable material, suchas polyethylene, covering the foil 11. Thus the sleeve 53 is moistureresistant. Also, sleeve 53 may be provided with two stripes of adhesive27 and 29 of heat-resistant pressuresensitive adhesive extending acrossthe sleeve, but these are provided on the plastic coating 15, ratherthan on the paper layer 9, as in the case of sleeve 25.

The sleeve 53 is folded in half on its longitudinal center line, withits plastic-coated face 15 on the outside and inserted with itsadhesive-carrying end first in the valve corner of the bag tube todispose the stripe of adhesive 27 against the plastic-coated face of theinnermost ply 5 and to cause the sleeve to become adhered thereto in thesame manner that sleeve 25 is adhered to the bag shown in FIG. 5. Afterthe valve corner of the bag is tucked in to form valve flap 35, aportion 53a of the sleeve is folded back on a transverse line 57'(corresponding to line 37) lying somewhat inward from the inward edge 39of the valve ap to extend back outward over the valve flap. This leavesa relatively short portion 53h of the sleeve 53 extending inwardly fromthe inner edge 39 of the valve flap, the plastic-coated face 15 of thisportion 55b being secured to the inside of the inner margin of the valveflap by reason of adhesive 27 securing it thereto. Stripe 29 of adhesiveoverlies the valve ap 35, i.e., the plastic-coated face of the outerply, and seals the sleeve to the valve flap.

An outer end portion 53C of .the sleeve is folded back inward toward theinner end of the sleeve and forms a cuff. The plastic-coated face `15 ofthis cuff 53C is thus on the inside of the -sleeve so that the plasticcoatings on each of the halves of the cuilE are in face to facerelation. It will be understood that the cuff 53e may be formed eitherbefore or after the sleeve is inserted into the bag.

As shown in FIGS. 8 and 9, the ends of the bag are closed .in a mannersuch as shown in Kindseth U.S. Patent 2,899,347 by rst providing aplurality of holes 59 through the bag plies and the sleeve. Aheat-scalable closure tape 61 of polyethylene, for example, is foldedover the ends of lthe bag and the holes. Heat and pressure are appliedto `the folded-over portions of the tape 61 to cause the latter toadhere to the bag plies and the sleeve and also to cause theheat-scalable material to flow through holes 59 to form plugs 63 whichjoin the two halves of the tape through the holes. After the bag hasbeen lled by means of a filling spout extending through the sleeve intothe bag, the outer end of the sieeve may be sealed by heat-sealingtogether .the two halves of the cuff 53C. The sleeve may then be tuckedinto the bag.

Thus, in the case of either the multiwall valve bag, as completed, ofFIGS. 6 and 7 or FIGS. 8 and 9, the bag has outer and inner plies 3 and5 adapted to prevent the ingress of atmospheric moisture .therethroughinto the bag contents. The inner ply 3 is also adapted to prevent theingress of any moisture in the intermediate plies 7 into the bagcontents. The valve formation is adapted substantially to prevent theingress of atmospheric moisture therethrough into the bag and also toprevent the ingress of atmospheric moisture between the sleeve (25 or53) and the valve flap 35 to the upper end edges 39 of the kraft paperintermediate plies 7. The top and bottom closures .prevent ingress ofatmospheric moisture therethrough, into the bag contents. While in thecase of the bag shown in FIGS. 6 and 7, as to which the paper layer ofsleeve 25 is on the outside, there may be some possibility of migrationof atmospheric moisture through the paper layer of the sleeve to theinterior of the bag, this is relatively minor. The construction of FIGS.8 and 9, wherein the plastic-coated foil layer of the sleeve 53 is onthe outside, effectively prevents the possibility of any such migrationof atmospheric moisture, since, after cuff 53C is heat-sealed, the paperlayer of the sleeve is sealed off from the atmosphere.

It will be understood that the outer ply of either bag shown may be aplastic-coated paper ply without metal foil, the plastic coating beingon the outside. In the case of the bag shown in FIGS. 8 and 9, whereinthe plastic-coated face 15 of the sleeve 53 faces the valve flap, thesea-ling at 27 may he by heat-sealing instead of by means of a separateadhesive. In such case, the stripe of adhesive 27 could be omitted fromsleeve 53, the attachment being made by utilizing the plastic 15 on thesleeve and on the inside of the .inner ply for heat-sealing. Where endclosures are used of such nature as to preclude moisture which haswicked through the intermediate plies of ,the bag from entering theinterior of the bag, it is possible that the adhesive at 29 could beomitted. Thus, if plugs 63 should be effective to keep moisture that maywick through the intermediate plies from entering the interior of thebag, the seal at Z9 may not be needed, although it is desirable toinclude this seal to avoid any possibility of entry of moisture in suchmanner.

In view of the above, it will be seen that the several objects of theinvention are achieved and other advan- .tageous results attained.

As various changes could be made in the above construction withoutdeparting from the scope of the invention, it is intended that allmatter -contained in the above description or shown in the accompanyingdrawlings shall be interpreted as illustrative and not in a limitingsense.

What is claimed is:

A bag having a valve at one of the corners at one end thereof, said bagbeing a multiwall bag having a plurality of plies, the inner plycomprising a layer of paper and having a moisture-resistant plasticcoating on the inside thereof, the outer ply comprising a laye-r ofpaper and having a moisture-resistant plastic coating on the outsidethereof, each ply having edge portions extending throughout the lengthof the bag which are sealed together thereby forming an individuallongitudinal seam for each ply, the longitudinal seam of the inner plybeing an inside-face-tinside-face longitudinal seam in which one edgeportion of the inner ply is folded back on the inner ply and has itsplastic-coated face adhered to the plastic-coated face .of the otheredge portion of the inner ply, the Valve being constituted by anintucked valve tlap at `said one corner and a Valve sleeve extendingfrom the valve flap, said sleeve comprising a layer of paper and havinga moisture-resistant plastic coating on one face thereof, said sleevebeing folded in half `on a generally central fold in 'line with .fthecentral fold of the valve ap, said sleeve having an end portion lappingthe inner end of the valve flap on the inside of the portion of theinner ply contained in the valve flap and being adhered to the inner endof the valve flap, said sleeve having a portion folded back on a foldline extending transversely with .respect to the sleeve and spacedinward from the inner end of the Valve ilap into a position overlyingand extending -out of the valve flap, the plasticcoated face of thesleeve being -on the out-side and said sleeve having an inturned cuff atits outer end, said folded-back portion of the sleeve being adhered tothe outside of the portion of the outer ply at the inner end of thevalve flap along a line extending completely across .the inner endportion of the valve i'lap in such manner as to prevent atmosphericmoisture which may enter between the sleeve and the outer ply of the bagfrom reaching the portions of the edges of the plies at the inner endedge of the valve ap, .and moisture-resistant closures at the ends ofthe bag.

References Cited by the Examiner UNITED STATES PATENTS 1,754,769 4/30Redington.

2,437,693 3/48 Hartman 229-625 2,496,796 2/50 Kardon 229-55 2,576,32211/51 Waters 229-625 2,714,983 8/55 Potdevin 229-625 2,731,046 1/56Bachner 161-216 X 2,811,300 10/57 Landell 229-625 2,975,074 3/61 Jankens117-76 3,040,967 6/62 Klein 229-625 FOREIGN PATENTS 1,066,481 10/59Germany.

FRANKLIN T. GARRE'IT, Primary Examiner.

